Roberto Mancini, the Manchester City manager, said last night that Manchester United had paid for their lack of ambition with defeat, in the game which may shift the balance of power in British football.

Roberto Mancini, the Manchester City manager, said last night that Manchester United had paid for their lack of ambition with defeat, in the game which may shift the balance of power in British football.

Sir Alex Ferguson accused Mancini of attempting to influence the officials by "badgering" them all night in the 1-0 defeat which takes City back to the top of the table on goal difference, but Mancini accused him of hypocrisy in a sarcastic swipe back. "Him? No? He doesn't do this! He doesn't talk to the referee to try to get decisions – never! But I never said anything against him. I was only talking to the fourth official."

The touchline dust-up between the two managers, in which Mancini's assistant David Platt and United kitman Albert Morgan intervened, followed Mancini's anger over Nigel de Jong's booking for a second-half challenge on Danny Welbeck. "I was talking with the fourth official about a foul on the pitch and Ferguson said some kind of words to me. I answered him and after it was finished," Mancini said. "But I can understand because at this moment the tension is high."

But the night, prefaced by City chairman Khaldoon al Mubarak speaking to City's players before kick-off, was about United lacking ambition. It was the first time in three years they have not had a shot on target in a Premier League game, with three blocked shots their sum total. "[The key was] that we wanted to win and they wanted a draw. This is the difference. This can happen," Mancini said.

Ferguson admitted that his side's bid for a 20th title was damaged. "Yes, I think they are in the driving seat now. They only need to win two games. It is not over yet. As long as there are games to play it is not over. But they have an eight-goal advantage and that is big at this stage of the season. It was a feisty game. We never tested their keeper and our crossing was poor. We had some control of the game but not enough."

United conceded to Vincent Kompany's header in first-half injury time. "If you lose a goal from a set-piece at this level of football, you only have yourselves to blame," Ferguson said.

Mancini declared: "Football is crazy, but it is important to believe in yourself when you have a bad moment. We were on top for 28 games and I think we deserve another chance. It is not finished and if we think it is finished, it will be a big mistake. We do have two tough games, though, and they have two easy games [against Swansea City and Sunderland]."

He said that Ferguson's defensive tactics did not surprise him. "No. It was important to play for a draw. With a draw, they knew the championship was finished." Kompany said: "We want [to win the league] so bad. Everybody in the team wants it so bad. A lot has been said about us but it comes down to football. A lot comes down to the dreams we had as children and winning things."

Welbeck left the Etihad on crutches last night and will undergo tests today to determine the extent of the damage.